Question: What do the following two equations represent? $5x-5y = -4$ $15x+15y = -5$
Explanation: Putting the first equation in $y = mx + b$ form gives: $5x-5y = -4$ $-5y = -5x-4$ $y = 1x + \dfrac{4}{5}$ Putting the second equation in $y = mx + b$ form gives: $15x+15y = -5$ $15y = -15x-5$ $y = -1x - \dfrac{1}{3}$ The slopes are negative inverses of each other, so the lines are perpendicular.